عن أنس بن مالكٍ رضي الله عنه قال: «ضَحَّى النَّبِيُّ صلى الله عليه وسلم بِكَبْشَيْنِ أَمْلَحَيْنِ أَقَرْنَيْنِ ذَبَحَهُمَا بِيَدِهِ، وَسَمَّى وَكَبَّرَ وَوَضَعَ رِجْلَهُ عَلَى صِفَاحِهِمَا».
[صحيح] - [متفق عليه]
Anas ibn Mālik (may Allah be pleased with him) reported: The Prophet (may Allah's peace and blessings be upon him) sacrificed two black and white horned rams, which he slaughtered with his own hand. He said: "Bismillāh (in the name of Allah), Allah Akbar (Allah is the Greatest)!" and put his foot on their necks.
Sahih/Authentic. - [Al-Bukhari and Muslim]
Another proof that Ud'hiyah (Eid sacrificial animal) is a confirmed act of Sunnah is that the Prophet (may Allah's peace and blessings be upon him) not only encouraged it, but he also performed it. He sacrificed two rams, black and white, each one having two horns. He slaughtered them with his noble hand, being a sublime form of worship that he performed himself. He mentioned the name of Allah, the Exalted, seeking His help so that it would be blessed. He also declared Allah's greatness by saying Allah Akbar, exalting Him, revering Him, singling Him out with worship, and displaying weakness and humility in front of Him, Blessed and Exalted. Since good treatment of the sacrificial animal is required, out of mercy toward the animal by swiftly making its soul depart the body, he placed his honorable foot upon their necks so they would not shake while being slaughtered, thereby lengthening the slaughter time which would be a torture to them, and Allah is Merciful to His creation.